Carrying your stuff is so handy. You don't risk anyone stealing anything and you don't have to worry about having one item here, one item it that tent, one item in the car, et cetera. And it's not even that heavy. Packing it properly and carrying it on the right height already helps a lot, and you get used to the weight anyway. Yeah, it still tiring, but it's re-enactment after all.
An added advantage is that people have to keep bullshit items at home because they cannot carry it. Unless your Olafson's brother of course, and you wreck yourself because you just have to bring a large heavy 1 litre bottle of beer.